The present invention relates to a portable cofferdam and method of use and more particularly to such a cofferdam which is adapted for use on generally horizontal underwater surfaces.
Various cofferdams have been disclosed in the prior art for providing access to submerged surfaces or structures. Most commonly, such cofferdams have been employed for performing maintenance or repairs or other types of work on the submerged surfaces or structures.
Generally, cofferdams are formed with an opening along one surface and are adapted for sealing engagement with the submerged surface or structure. Water may then be pumped from the cofferdam in order to provide access to the surface or structure with which the cofferdam is engaged.
Generally, it has been common practice in the past to position the cofferdam with its open surface adjacent the submerged surface requiring repairs or the like. With the cofferdam so positioned, water is then evacuated or removed from the interior of the cofferdam, the cofferdam being held in place either by external means or partially or entirely by the pressure differential between the interior and exterior of the cofferdam. However, where cofferdams have been secured in place by such differential pressures, they depended entirely on the differential pressure between the exterior of the cofferdam and the entire interior of the cofferdam. Also, where the cofferdam is held in place by such a pressure differential, additional restraining means are necessary to secure the cofferdam while its interior is being evacuated. With all such cofferdams, sealing means were provided about the periphery of the cofferdam for sealing engagement with the submerged surface or structure.
In any event, most such cofferdams have been relatively difficult to install upon the submerged surfaces or structures partly because of the difficulty of positioning the cofferdam and securing it in place while water is evacuated from its interior. The use of such cofferdams in the past has thus been relatively expensive and time-consuming.
Accordingly, there has been found to remain a need for a portable cofferdam for providing working access to underwater surfaces where the cofferdam is relatively easy to install and evacuate. More particularly, there has been found to remain a need for a bottom-seated portable cofferdam to provide working access for underwater surfaces which are generally horizontal.